Method and apparatus for detection and control of dc arc faults

ABSTRACT

A method and apparatus for managing DC arc faults. At least a portion of the method is performed by a controller comprising at least one processor. In one embodiment, the method comprises analyzing a signature of a signal of a power converter and determining, based on analysis of the signature, whether an arc fault exists.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit of U.S. provisional patent applicationSer. No. 61/227,949, filed Jul. 23, 2009, which is herein incorporatedin its entirety by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present disclosure generally relate to renewableenergy power systems and, more particularly, to a method and apparatusfor detecting series and parallel DC arc faults in a DC circuit of aphotovoltaic (PV) system.

2. Description of the Related Art

Solar modules have historically been deployed in mostly remoteapplications, such as remote cabins in the wilderness or satellites,where commercial power was not available. Due to the high cost ofinstallation, solar modules were not an economical choice for generatingpower unless no other power options were available. However, theworldwide growth of energy demand is leading to a durable increase inenergy cost. In addition, it is now well established that the fossilenergy reserves currently being used to generate electricity are rapidlybeing depleted. These growing impediments to conventional commercialpower generation make solar modules a more attractive option to pursue.

Solar modules, or photovoltaic (PV) modules, convert energy fromsunlight received into direct current (DC). The PV modules cannot storethe electrical energy they produce, so the energy must either bedispersed to an energy storage system, such as a battery or pumpedhydroelectricity storage, or dispersed by a load. One option to use theenergy produced is to employ inverters to convert the DC current into analternating current (AC) and couple the AC current to the commercialpower grid. The power produced by such a distributed generation (DG)system can then be sold to the commercial power company, or used tooffset local consumption of electricity by local loads.

In order to mitigate potential safety hazards during such DC to AC powerconversion, a DC circuit of the PV system must often be protected withfuses, and specific system design constraints must be followed. Inaddition, a Ground Fault Detection and Interruption circuit is oftenrequired. Such protective measures may also be utilized in DC/DC powerconverters. These protective measures, however, do not provide reliabledetection or mitigation of DC arc faults during power conversion (i.e.,DC/DC or DC/AC power conversion). Such arcs are extremely dangerous, asthe DC PV system will continue to provide energy into a short circuit oran arcing circuit as long as the PV modules continue to be irradiatedwith light, potentially leading to a fire.

Therefore, there is a need for a method and apparatus for automaticallydetecting series and parallel DC arc faults and extinguishing thosearcs.

SUMMARY OF THE INVENTION

Embodiments of the present invention generally relate to a method andapparatus for managing DC arc faults. At least a portion of the methodis performed by a controller comprising at least one processor. In oneembodiment, the method comprises analyzing a signature of a signal of apower converter and determining, based on analysis of the signature,whether an arc fault exists.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 is a block diagram of a system for inverting solar generated DCpower to AC power in accordance with one or more embodiments of thepresent invention;

FIG. 2 is a block diagram of a power converter in accordance with one ormore embodiments of the present invention;

FIG. 3 is a flow diagram of a method for identifying and managing a DCarc fault in a power conversion system in accordance with one or moreembodiments of the present invention; and

FIG. 4 is a flow diagram of a method for identifying a DC arc faultbased on power changes in a power conversion system in accordance withone or more embodiments of the present invention.

DETAILED DESCRIPTION

FIG. 1 is a block diagram of a system 100 for inverting solar generatedDC power to AC power in accordance with one or more embodiments of thepresent invention. This diagram only portrays one variation of themyriad of possible system configurations. The present invention canfunction in a variety of environments and systems.

The system 100 comprises a plurality of power converters 102 ₁, 102 ₂ .. . 102 _(n), collectively referred to as power converters 102, aplurality of PV modules 104 ₁, 104 ₂ . . . 104 _(n), collectivelyreferred to as PV modules 104, an AC bus 106, and a load center 108. Twoinput terminals of each power converter 102 ₁, 102 ₂ . . . 102 _(n) arecoupled to two output terminals of a corresponding PV module 104 ₁, 104₂ . . . 104 _(n); i.e., the power converters 102 and the PV modules 104are coupled in a one-to-one correspondence.

The power converters 102 each comprise a DC/DC conversion module coupledto a DC/AC inversion module, as described below with respect to FIG. 2,for inverting the DC power generated by the PV modules 104 to AC power(i.e., AC current); alternatively, a single stage converter may convertDC directly to AC. The power converters 102 are coupled to the AC bus106, which in turn is coupled to the load center 108. In someembodiments, the load center 108 houses connections between incomingpower lines from a commercial AC power grid distribution system (“grid”)and the AC bus 106. Additionally or alternatively, the AC bus 106 may beregulated by a battery-based (or other energy storage source) inverterand/or a rotating machine generator. The power converters 102 meter outAC current that is in-phase with the AC power grid voltage, and thesystem 100 couples the generated AC power to the power grid via the loadcenter 108. Additionally or alternatively, the generated AC power may besupplied directly to commercial and/or residential systems via the loadcenter 108, and/or stored for later use (e.g., utilizing batteries,heated water, hydro pumping, H₂O-to-hydrogen conversion, or the like).

In some alternative embodiments, the power converter 102 may notcomprise a DC/DC converter (i.e., the power converter 102 comprises asingle-stage DC/AC inverter) and a separate DC/DC converter may becoupled between each PV module 104 and each power converter 102 (i.e.,one DC/DC converter per power converter/PV module pair). In otheralternative embodiments, each of the power converters 102 may be a DC/DCconverter to convert the DC power generated by the PV modules 104 intoDC at a different voltage. In such other alternative embodiments, theconverted DC power from the power converters 102 may be supplied tocommercial and/or residential DC systems, and/or the produced energy maybe stored, for example, in storage batteries.

In still other alternative embodiments, multiple PV modules 104, coupledin series and/or parallel configurations, may be coupled to a singlepower converter 102. For example, the PV modules 104 of the system 100may be coupled to a single centralized power converter 102 that invertsthe DC power from the PV modules 104 to AC power (i.e., a centralizedinverter). In some such alternative embodiments, a DC/DC converter maybe coupled between the PV modules 104 and the centralized powerconverter 102; alternatively, the centralized power converter 102 may bea DC/DC converter that converts the DC power generated by the PV modules104 into DC at a different voltage. Any of the aforementionedconfigurations for converting DC to AC may, in some embodiments, becomprised of a single DC/AC converter (i.e., a single stage DC/ACconverter).

In order to control the power conversion performed, the power converters102 may measure (for example, at intervals ranging from microseconds totens of milliseconds) one or more of DC current and voltage from the PVmodules 104 as well as AC current and voltage generated by the powerconverters 102. In accordance with one or more embodiments of thepresent invention, the power converters 102 may utilize at least aportion of the measured data to determine whether a DC arc fault ispresent and to control such an arc fault, as further described below. Insome embodiments, one or more signatures based on one or more signals ofa power converter 102 (e.g., DC current, DC voltage, AC current, ACvoltage, DC power, AC power, a derivative of any of such signals, acombination of any of such signals, or the like) may be analyzed todetermine whether a DC arc fault exists. The DC arc fault may consist ofa parallel arc across the power converter input terminals or acrossoutput terminals of the DC/DC conversion module of the power converter102. Alternatively, the DC arc fault may consist of a series arc, forexample, between one of the PV module output terminals and the coupledpower conversion module input terminal, or between an output terminal ofthe power converter DC/DC conversion module and the coupled DC/ACinversion module terminal.

FIG. 2 is a block diagram of a power converter 102 in accordance withone or more embodiments of the present invention. The power converter102 comprises a power conversion circuit 202, a controller 204, a DCcurrent sampler 206, a DC voltage sampler 208, an AC current sampler210, an AC voltage sampler 212, and a DC input shorting mechanism 228.

The power conversion circuit 202 comprises a DC/DC conversion module 230and a DC/AC inversion module 232. The DC/DC conversion module 230 iscoupled via two input terminals to the PV module 104 and via two outputterminals to two input terminals of the DC/AC inversion module 232,which is further coupled via two output terminals to the load center108. The DC/DC conversion module 230 and the DC/AC inversion module 232are each coupled to the controller 204. The DC/DC conversion module 230and the DC/AC inversion module 232 act to convert the DC power from thePV modules 104 to a second DC power and then to an AC power,respectively, based on control signals from the controller 204. As such,the power conversion circuit 202 converts DC current received from thePV module 104 to AC current with the controller 204 providing operativecontrol and driving the power conversion circuit 202 to inject thegenerated AC output current in phase with the grid, as required by therelevant standards.

The DC current sampler 206 is coupled to an input terminal of the powerconversion circuit 202, and the DC voltage sampler 208 is coupled acrossthe two input terminals of the power conversion circuit 202. The ACcurrent sampler 210 is coupled to an output terminal of the powerconversion circuit 202, and the AC voltage sampler 212 is coupled acrossthe two output terminals of the power conversion circuit 202. The DCcurrent sampler 206, the DC voltage sampler 208, the AC current sampler210, and the AC voltage sampler 212 are each coupled to the controller204. Additionally, the DC input shorting mechanism 228 is coupled acrossthe two power conversion circuit input terminals and to the controller204.

The controller 204 comprises at least one central processing unit (CPU)214, which is coupled to support circuits 216 and to a memory 218. TheCPU 214 may comprise one or more conventionally availablemicroprocessors or digital signal processors (DSPs); additionally oralternatively, the CPU 214 may include one or more application specificintegrated circuits (ASIC). The support circuits 216 are well knowncircuits used to promote functionality of the CPU 214. Such circuitsinclude, but are not limited to, a cache, power supplies, clockcircuits, buses, network cards, input/output (I/O) circuits, and thelike. The controller 204 may be implemented using a general purposeprocessor that, when executing particular software, becomes a specificpurpose processor for performing various embodiments of the presentinvention.

The memory 218 may comprise random access memory, read only memory,removable disk memory, flash memory, and various combinations of thesetypes of memory. The memory 218 is sometimes referred to as main memoryand may, in part, be used as cache memory or buffer memory. The memory218 generally stores the operating system (OS) 220 of the controller204. The OS 220 may be one of a number of commercially availableoperating systems such as, but not limited to, Linux, Real-TimeOperating System (RTOS), and the like.

The memory 218 may store various forms of application software, such asa conversion control module 222 for controlling the operation of thepower conversion circuit 202. The conversion control module 222 mayreceive the sampled DC and AC current and voltage values and utilizesuch data to provide the control and switching signals for the powerconversion circuit 202. Additionally, the memory 218 may comprise adatabase 224 for storing data, and a waveform processing module 226 fordetermining and managing DC arc faults (e.g., determining an arc type ofseries or parallel, determining voltage and current characteristics, andthe like), as described in detail below. The database 224 may store datarelated to the power conversion and/or data related to processingperformed by the waveform processing module 226; for example, sampled DCand AC voltage and current values, computed current and/or voltageslope, computed changes in current and/or voltage slope over time, oneor more thresholds for use in determining a DC arc fault event, DC arcfault event intervals, voltage and current correlations, and the like.In some embodiments, the conversion control module 222, database 224,and/or waveform processing module 226, or portions thereof, may beimplemented in software, firmware, hardware, or a combination thereof.

As part of controlling power production by the power conversion circuit202, the DC current sampler 206 and the DC voltage sampler 208 samplethe DC current and voltage, respectively, generated by the PV module 104and provide such sampled DC current and voltage values to the controller204. Additionally, the AC current sampler 210 and the AC voltage sampler212 sample the AC current and voltage, respectively, at the output ofthe power conversion circuit 202 and provide such sampled AC current andvoltage values to the controller 204. The input signals to each of thesamplers are filtered, for example via traditional analog filtertechniques, digital signal processing, or similar techniques, and ananalog-to-digital (A/D) conversion is performed utilizing standard A/Dtechnology. The resulting instantaneous values, or samples, of DCcurrent, DC voltage, AC current, and AC voltage may be stored digitallyin the database 224 for use by the waveform processing module 226 indetermining whether a DC arc faults exists, as described below.

In accordance with one or more embodiments of the present invention, thewaveform processing module 226 utilizes the sampled DC current andvoltage values, which respectively define DC current and voltagesignatures that characterize the DC circuit current and voltage overtime, to determine an occurrence of a DC arc fault. The characteristicsof an arc fault may be extracted from the sampled current and voltagevalues by filtering unwanted artifacts from the sampled data andquantizing the dynamic behavior of the voltage and current values, aswell as their relationship to each other. In some embodiments, thewaveform processing module 226 analyzes, for example, generally everymillisecond (msec) but as often as every microsecond (μsec), the DCcurrent and voltage signatures defined by at least a portion of the DCcurrent and voltage samples in order to identify an arc fault; for suchanalysis, sampled current and/or voltage values may be averaged over aperiod of, for example, approximately 1 msec for analysis. In otherembodiments, the signatures may be updated analyzed more or lessfrequently. In some embodiments, the waveform processing module 226 mayanalyze at least several tens of microseconds to a few milliseconds ofdata to identify characteristics indicating a DC arc fault (i.e., aseries arc or a parallel arc).

In one or more alternative embodiments, DC voltage and AC currentsignatures defined by sampled DC voltage and sampled AC current,respectively, may be utilized to determine the presence of a DC arcfault (both current and voltage signatures are utilized to determine theexistence of an arc fault).

In order to identify a DC arc fault, the waveform processing module 226analyzes the DC current signature for a change in polarity or a rapidchange in slope (e.g., on the order of 0.1 amp/microsecond in someembodiments) indicating a potential DC arc fault. During normaloperating conditions (i.e., no arc faults), the DC current polarityshould always be positive and change in slope of DC current is normallydue to changes in the commanded output current of the power converter102; any fast change in current polarity or a change in slope that isnot due to a change in commanded output current is suspect as being dueto an arc fault. Slower changes may be due to changes in irradiance, andwill not be detected as an arc fault. If a potential DC arc fault isidentified, the waveform processing module 226 compares the DC currentsignature to the DC voltage signature, e.g., the DC current and voltagesare analyzed for coincidence and polarity that are not the result ofchanges in commanded output current of the power converter 102. If,based on such comparison, it is determined that a DC arc fault signaturematch exists (i.e., one or more characteristics of the DC current and/orDC voltage signature are indicative of a DC arc fault), the DC currentpolarity is utilized to differentiate whether the DC circuit isexperiencing a series or parallel arc event. In some embodiments, a DCarc fault signature match may be determined based on current and/orvoltage changes, such as a maximum change in current and/or voltage overtime.

If the DC current polarity has remained positive, a series arc hasoccurred and the waveform processing module 226 causes the powerconverter 102 to cease power production. If the DC current polarity hasa negative occurrence, a parallel arc has potentially occurred. Duringnormal operation, i.e., when no arc faults exist, the DC currentpolarity should always be positive. However, when a parallel arc occurs,a large amount of negative current occurs for a time on the order of amillisecond (e.g., due to a violent discharge of one or more capacitorslocated across the DC input of the power converter; such a dischargedoes not occur in the event of a series arc). As a result of determiningthat the DC current polarity is negative, the waveform processing module226 drives the controller 204 to inhibit power production by the powerconverter 102 and to lock the DC input shorting mechanism 228, whichprovides a short circuit across the input to the power conversioncircuit 202. In order to verify that a parallel arc has, in fact,occurred, the waveform processing module 226 analyzes the DC currentsignature for DC current fluctuations, for example, as determined bycomparison to a threshold (e.g., changes in current that are much morerapid than under normal operating conditions). Specific di/dt willdepend on the length of the DC wire run, the normal DC voltage, and thepower rating of the DC source as it interacts with the inputcharacteristics of the power converter 102; di/dt in excess of thenormal control mechanism (e.g., as compared to a threshold) may beindicative of an arc fault. If the DC current is not fluctuating, aparallel arc is confirmed and the DC input shorting mechanism 228remains locked. If the DC current is fluctuating, the arc is a seriesarc and the waveform processing module 226 drives the controller 204 tounlock the DC input shorting mechanism 228 (i.e., to open the DCterminals) while continuing to lock out the power production.

In some embodiments, the power converter 102 may employ an auto-restarttechnique for attempting to restart the power converter 102 and resumepower production after some period of time, for example on the order ofa few minutes subsequent to the arc detection and termination of powerproduction. The power converter 102 may attempt such a restart one ormore times before sustaining the termination of power production in theevent that the arc fault remains or recurs.

In one or more alternative embodiments, occurrence of a DC arc fault maybe determined based on a power signature generated from the sampled DCcurrent and voltage data, or from the sampled AC current and DC voltagedata.

FIG. 3 is a flow diagram of a method 300 for identifying and managing aDC arc fault in a power conversion system in accordance with one or moreembodiments of the present invention. In some embodiments, such as theembodiment described below, the power conversion system comprises one ormore power converters, such as DC/AC inverters, coupled to one or morePV modules. In such embodiments, the DC/AC inverters may each comprise aDC/DC conversion module followed by a DC/AC inversion module to invertthe DC power generated by the PV modules to AC power (e.g., the powerconverters 102 comprising the DC/DC conversion modules 230 and the DC/ACinversion modules 232); alternatively, the DC/AC inverters may utilize asingle DC/AC conversion stage. The generated AC power may then becoupled to an AC power grid, provided directly to commercial and/orresidential AC powered devices, and/or stored for later use (e.g.,utilizing batteries, heated water, hydro pumping, H₂O-to-hydrogenconversion, or the like). In one or more alternative embodiments, thepower converters may be DC/DC converters for converting the DC powergenerated by the PV modules into DC at a different voltage.

In some embodiments, a signature based on one or more signals of a powerconverter (e.g., DC current, DC voltage, AC current, AC voltage, DCpower, AC power, a derivative of any of such signals, a combination ofany of such signals, or the like) may be analyzed to determine whether aDC arc fault exists.

The method 300 begins at step 302 and proceeds to step 304, where DCcurrent and DC voltage from the PV module(s) coupled to a powerconverter in the power conversion system are sampled. The measured DCcurrent and DC voltage may be filtered, for example by traditionalanalog filter techniques, digital signal processing, or similartechniques, and an A/D conversion may be performed utilizing standardA/D technology. The resulting instantaneous DC current value andinstantaneous DC voltage value (i.e., the DC current and voltagesamples) may be stored, for example, within a memory of the powerconverter, such as memory 218. In one or more embodiments, AC currentand/or AC voltage generated by the power converter may be analogouslysampled and stored for use in identifying and managing DC arc faults,such as a DC arc fault at the input or the output of the powerconverter's DC/DC conversion module.

At step 308, a DC current signature is analyzed to determine whether apotential arc has occurred. The DC current signature is defined by thesampled DC current and characterizes the DC current over time. In someembodiments, the DC current signature is analyzed for a rapid change inslope (e.g., on the order of 0.1 amp/microsecond in some embodiments) ora change in polarity to indicate a potential arc, as previouslydescribed.

The method 300 proceeds to step 310, where a determination is madewhether a potential arc has been identified based on the analysis ofstep 308. If the result of such determination is no, the method 300proceeds to step 334. At step 334, a determination is made whether tocontinue operation. If, at step 334, the result of the determination isyes, the method 300 returns to step 304; if the result of thedetermination is no, the method 300 proceeds to step 336 where it ends.The determination in step 334 may be based upon the repetitiveoccurrence of the indication of an arc fault which may indicate anintermittent fault, or may indicate a failure in the measurement andcontrol system.

If, at step 310, the result of the determination is yes (i.e., apotential arc has been identified), the method 300 proceeds to step 312.At step 312, the DC current signature is compared to a DC voltagesignature. The DC voltage signature is defined by the sampled DC voltageand characterizes the DC voltage over time. The DC current and voltagesignatures are compared to identify characteristics consistent with a DCarc fault signature (i.e., to determine whether a DC arc fault signaturematch exists). In some embodiments, the DC current and voltagesignatures are analyzed for coincidence and polarity that are not theresult of changes in commanded output current of the power converter. Atstep 314, a determination is made whether a DC arc fault signature matchexists based on the comparison of step 312. If the result of suchdetermination is no, the method 300 proceeds to step 334; if the resultof such determination is yes, the method 300 proceeds to step 316.

At step 316, the DC current polarity is utilized to differentiatewhether the DC circuit is experiencing a series or parallel arc event.If the DC current polarity has remained positive, it is determined thata series arc has occurred; if the DC current polarity has a negativeoccurrence, it is determined that a parallel arc has potentiallyoccurred. At step 318, a determination is made whether a series or aparallel arc is identified based on the analysis of step 316. If theresult of such determination is that a series arc has occurred, themethod 300 proceeds to step 330. At step 330, power production by thepower converter is inhibited; the method 300 then proceeds to step 336where it ends.

If, at step 318, the result of the determination is that a parallel archas potentially occurred, the method 300 proceeds to step 320. At step320, power production by the power converter is inhibited. At step 322,DC terminals at the input of the power converter are shorted, forexample by locking a DC input shorting mechanism (e.g., DC inputshorting mechanism 228). At step 324, the DC current signature isanalyzed for DC current fluctuations, for example as determined bycomparison to a threshold (e.g., changes in current that are much morerapid than under normal operating conditions); if the DC current is notfluctuating, a parallel arc is confirmed. At step 326, a determinationis made whether the parallel arc is confirmed based on the analysis ofstep 324. If the result of such determination is no, the arc isdetermined to be a series arc and the method 300 proceeds to step 328,where the shorted DC terminals are opened, for example by unlocking theDC input shorting mechanism. The method 300 then proceeds to step 330and the power production by the power converter remains locked out. If,at step 326, the result of such determination is yes (i.e., a parallelarc is confirmed), the method 300 proceeds to step 332, where the DCinput terminals remain shorted. The method 300 then proceeds to step 336where it ends.

In one or more alternative embodiments, the method 300 may additionallyor alternatively utilize the sampled AC current data and/or the sampledAC voltage data for determining and managing an occurrence of a DC arcfault. In some embodiments, the method 300 may comprise steps for anauto-restart technique for attempting to restart the power converter andresume power production after some period of time, for example on theorder of a few minutes subsequent to the arc detection and terminationof power production. Such a restart may be attempted one or more timesbefore sustaining the termination of power production in the event thatthe arc fault remains or recurs.

FIG. 4 is a flow diagram of a method 400 for identifying a potential DCarc fault based on power changes in a power conversion system inaccordance with one or more embodiments of the present invention. Insome embodiments, such as the embodiment described below, the powerconversion system comprises one or more power converters, such as DC/ACinverters, coupled to one or more PV modules. In such embodiments, theDC/AC inverters may each comprise a DC/DC conversion module followed bya DC/AC inversion module to invert the DC power generated by the PVmodules to AC power (e.g., the power converters 102 comprising the DC/DCconversion modules 230 and the DC/AC inversion modules 232). Thegenerated AC power may then be coupled to an AC power grid, provideddirectly to commercial and/or residential AC powered devices, and/orstored for later use (e.g., utilizing batteries, heated water, hydropumping, H₂O-to-hydrogen conversion, or the like). In one or morealternative embodiments, the power converters may be DC/DC convertersfor converting the DC power generated by the PV modules into DC at adifferent voltage.

The method 400 begins at step 402 and proceeds to step 404, where DCcurrent and DC voltage from the PV module(s) coupled to a powerconverter in the power conversion system are sampled. The measured DCcurrent and DC voltage may be filtered, for example by traditionalanalog filter techniques, digital signal processing, or similartechniques, and an A/D conversion may be performed utilizing standardA/D technology. At step 406, the resulting instantaneous DC current andvoltage values are used to compute an instantaneous DC power. Theinstantaneous DC power value, as well as the instantaneous DC currentand voltage values, may be stored, for example within a memory of thepower converter, such as memory 218. In one or more alternativeembodiments, AC current and AC voltage from the power converter may beanalogously sampled and utilized to obtain AC power measurements foridentifying DC arc faults, such as a DC arc fault at the input or theoutput of the power converter's DC/DC conversion module.

At step 410, a DC power signature is analyzed to determine whether apotential arc has occurred. The DC power signature is defined by theinstantaneous DC power values and characterizes the DC power over time.In some embodiments, a rapid power decrease in the DC power signature,for example as determined by comparison to a threshold (e.g., amicrosecond change in power more than, for example, a few percent of therated power that does not coincide with a change in current command fromthe power converter power control system) indicates a potential arc;additionally or alternatively, the power change dp/dt may be evaluatedfor determining whether a potential arc has occurred.

The method 400 proceeds to step 412, where a determination is madewhether a potential DC arc fault has been identified based on theanalysis of step 410. If the result of such determination is no (i.e.,no potential DC arc fault), the method 400 proceeds to step 414, where adetermination is made whether to continue operation. If the result ofsuch determination at step 414 is yes (i.e., continue operation), themethod 400 returns to step 404. If the result of such determination isno, the method 400 proceeds to step 416 where it ends.

If, at step 412, the result of the determination is yes (i.e., apotential DC arc fault), the method 400 proceeds to step 312 of themethod 300.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow.

1. A method for managing arc faults, at least a portion of the methodbeing performed by a controller comprising at least one processor, themethod comprising: analyzing a signature of a signal of a powerconverter; and determining, based on analysis of the signature, whetheran arc fault exists, wherein analyzing the signature comprises (i)analyzing the signature to identify a potential arc fault, wherein thesignature is based on a current of the power converter; and (ii)comparing, upon identifying the potential arc fault, the signature witha second signature for determining an arc fault signature match thatidentifies the arc fault, wherein the second signature is based on avoltage of the power converter; and determining polarity of a DC currentof the power converter; and differentiating between a series arc and aparallel arc based on the polarity.
 2. The method of claim 1, furthercomprising inhibiting power production by the power converter upondetermining that the arc fault exists.
 3. The method of claim 1, furthercomprising applying a short circuit across DC input terminals of thepower converter upon identifying the parallel arc.
 4. The method ofclaim 3, further comprising analyzing the signature for currentfluctuations, wherein a non-fluctuating current confirms the parallelarc.
 5. The method of claim 4, further comprising removing the shortcircuit upon determining a fluctuating current.
 6. The method of claim1, wherein the series arc is identified when the polarity is positiveand the parallel arc is identified when the polarity is negative.
 7. Themethod of claim 1, wherein the signature is a DC current signature basedon a DC current of the power converter and the second signature is a DCvoltage signature based on a DC voltage of the power converter.
 8. Themethod of claim 1, wherein determining whether the arc fault existscomprises distinguishing between irradiance-generated changes in thesignature and arc-generated changes in the signature.
 9. An apparatusfor managing arc faults, comprising: a waveform processing module,adapted for coupling to a power conversion circuit, for analyzing asignature of a signal of the power conversion circuit and determining,based on analysis of the signature, whether an arc fault exists, whereinanalyzing the signature comprises (i) analyzing the signature toidentify a potential arc fault, wherein the signature is based on acurrent of the power conversion circuit; and (ii) comparing, uponidentifying the potential arc fault, the signature with a secondsignature for determining an arc fault signature match that identifiesthe arc fault, wherein the second signature is based on a voltage of thepower conversion circuit; and wherein the waveform processing modulefurther determines polarity of a DC current of the power conversioncircuit; and differentiates between a series arc and a parallel arcbased on the polarity.
 10. The apparatus of claim 9, wherein thewaveform processing module inhibits power production by the powerconversion circuit upon determining that the arc fault exists.
 11. Theapparatus of claim 9, further comprising a shorting mechanism forapplying a short circuit across DC input terminals of the powerconversion circuit upon the parallel arc being identified.
 12. Theapparatus of claim 11, wherein the waveform processing module furtheranalyzes the signature for current fluctuations, wherein anon-fluctuating current confirms the parallel arc.
 13. The apparatus ofclaim 12, wherein the short circuit is removed upon determining afluctuating current.
 14. The apparatus of claim 9, wherein the seriesarc is identified when the polarity is positive and the parallel arc isidentified when the polarity is negative.
 15. The apparatus of claim 9,wherein the signature is a DC current signature based on a DC current ofthe power conversion circuit and the second signature is a DC voltagesignature based on a DC voltage of the power conversion circuit.
 16. Theapparatus of claim 9, wherein determining whether the arc fault existscomprises distinguishing between irradiance-generated changes in thesignature and arc-generated changes in the signature.
 17. A system formanaging arc faults, comprising: a photovoltaic (PV) module; a powerconverter coupled to the PV module, wherein the power convertercomprises a waveform processing module coupled to a power conversioncircuit, for analyzing a signature of a signal of the power conversioncircuit, the waveform processing module for analyzing a signature of asignal of the power converter and determining, based on analysis of thesignature, whether an arc fault exists, wherein analyzing the signaturecomprises (i) analyzing the signature to identify a potential arc fault,wherein the signature is based on a current of the power conversioncircuit; and (ii) comparing, upon identifying the potential arc fault,the signature with a second signature for determining an arc faultsignature match that identifies the arc fault, wherein the secondsignature is based on a voltage of the power conversion circuit; andwherein the waveform processing module further determines polarity of aDC current of the power conversion circuit; and differentiates between aseries arc and a parallel arc based on the polarity.